It is known to provide a metal structural part with a lining or layer of ceramic material for protection of the metal part against high temperatures and corrosion by hot gases. These layers are applied by means of plasma spraying or vaporization. In this way, the ceramic layers are formed with an open, inner structure having large, open pores or cavities constituting an open grain structure. The open, inner structure is formed either in the course of manufacture or intentionally. The open structure is formed at least in part, by microcracks in the ceramic layer. Chemical and physical changes can occur at the surfaces of the open, inner pores due to thermal loads and hot gases, and these may lead to the formation of additional microcracks in the protective ceramic layer. The progression of cracking can ultimately lead to a complete breakdown of the heat insulation layer.
Another disadvantage of the ceramic, heat insulation layers with open, inner pore surfaces is that they cannot effectively protect the structural part against oxidation.